Pipe bending press



6. HElDE PIPE BENDING PRESS July 1, 1969 I of 2 Sheet Filed Nov. 15, 1967 INVENTOR. Q Z A z/ $454 lllll Sheet ,5 of2 July 1, 1969 G. HEIDE I PIPE BENDING PRESS Filed Nov. 15. 1967 INVENTOR. 62,66 4a a J ,&

United States Patent US. Cl. 72-453 8 Claims ABSTRACT OF THE DISCLOSURE The pipe bending press utilizes a hydraulic ram within which slides a hollow piston. A pipe bending mandrel has the end of its straight portion so formed that when this end is inserted into the hollow piston, it will be secured against endwise movement thereafter outwardly of the piston. The end of the piston has a push surface through which it is guided for sliding movement on the mandrel, this push surface fitting against the end of the last pipe section on the mandrel for pushing this section and the sections before it longitudinally of the mandrel and over a bent end of the mandrel.

Pipe bending press This invention relates to a pipe bending press of that type in which a series of short lengths of pipe are bent into elbows ranging from a few degrees to 180. Presses of this type are well known in the art and generally comprise a mandrel having a long straight portion and one bent end. Short sections of tubular pipe are placed on the long straight portion of the mandrel and the mandrel is then secured at the end of its straight portion to a press and held against longitudinal movement. The press has a hydraulic ram at each side of the mandrel, and the two pistons of the hydraulic rams are connected by a collar which is fitted against the section of tubular pipe nearest the end of the straight portion of the mandrel. The bent portion of the mandrel is heated, as are the pipe sections approaching the bent portion, while pressure is applied by the collar to push the pipe sections over the mandrel and to shape them to the bent end of the mandrel.

In a machine of the particular class, difiiculties are encountered because the collar is actuated by two pistons which may or may not apply equal pressures at all times. Further, it is obvious that each of the piston rods and also the collar must be accurately guided, and that binding and other difliculties may occur because of the necessity for a plurality of guiding means. Further, the securing of the mandrel becomes complicated, because it must be held in particular relation to the collar and the guiding means.

In the machine which I have contributed, I use but a single hydraulic ram. Further, this single hydraulic ram utilizes a hollow piston into which the end of the straight portion of the mandrel may be inserted. As a further feature of the invention, I utilize a push surface at the end of the hollow piston, this push surface fitting on the cylindrical surface of the mandrel so that there is a mutual guidance between the mandrel and the piston. Further, the piston will of necessity and inherently operate against the end surface of the last of the pipe sections on the mandrel.

As a still further feature of the invention, there are means within the hollow piston secured to the cylinder, which readily accept the mandrel and hold it against endwise movement out of the cylinder and the hollow piston.

It is still a further feature of this portion of the invention that the return movement of the hollow piston, after completing the ejection of the pipe sections in bent form from the mandrel, will bring about an opening of the propriation of my invention 3,452,583 Patented July 1, 1969 push surface automatically, for the removal of the mandrel then in the machine and a substitution of a new mandrel on which are mounted further pipe sections. Thereafter, slight movement of the hollow piston will bring the push surface to a functioning relationship relatively to the mandrel and the pipe sections on the mandrel, with the machine immediately ready for functioning.

Because of the mutual guiding that takes place between the cylinder, the piston and the mandrel, there is no need for additional guiding means as will be fully appreciated by those skilled in the art. I, therefore, contribute to the art a machine that is extremely simple and may be manufactured of relatively light parts, the functioning parts of the machine being inherently accurate and self aligning in their operation.

I have thus outlined rather broadly the more important features of my invention in order that the detailed description thereof that follows may be better understood, and in order that my contribution to the art may be better appreciated. There are, of course, additional features of my invention that will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception on which my disclosure is based may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of my invention. It is important, therefore, that the claims be regarded as including such equivalent constructions as do not depart from the spirit and scope of my invention, in order to prevent the apby those skilled in the art.

Referring now to the drawings,

FIGURE 1 is a general view of the press in which my invention is embodied;

FIGURE 2 is an enlarged longitudinal section through the double acting ram of my press; and

FIGURE 3 is an end view of the device for holding the mandrel within the hollow piston and illustrates the manner of assembly of the mandrel to this device.

Referring now more particularly to the drawings, the cylinder of my hydraulic ram is resignated by reference numeral 1, while the hollow piston is designated by reference numeral 3. The push surface of the hollow piston is designated generally by reference numeral 2. This push surface 2 utilizes two jaws 20 each rotated on a pivot axis 21, and normally movable through suitable spring means (not shown) into the position illustrated in FIGURE 2.

Hollow piston 3 has at one end a piston head 4, which is centrally bored at 4a for a rod 5 which is fixed to the end wall 22 of the cylinder 1 of the hydraulic ram, and preferably also to suitable support means not shown. Hydraulic fluid is admitted to the cylinder 1 through a passage 9 at one side of the piston head 4 and a passage 10 at the other side of the piston head 4, and it is obvious that in this manner; the piston head 4 and the piston 3 will be reciprocated in the cylinder 1. Reference numeral 11 designates a feeding device of known type through which pipe sections 12 may be applied to a mandrel, while 13 indicates an oven for heating the end of the mandrel.

The mandrel is itself designated by reference numeral 7, and is formed, as already indicated, with a long straight portion and a bent portion. The series of pipe sections are applied to the long straight portion of the mandrel 7 and are adapted to be pushed over the mandrel and over the bent portion thereof to form elbows. Operation of the entire machine is under the control of a control panel 8.

The rod 5 fixed to the cylinder of the ram has at one end thereof a holding device 6, the end surface 31 of which is best illustrated in FIGURE 3. A slot 30 is formed in the end surface 31 and this slot has a widened upper end and a relatively narrow lower end. The relatively wide portion of the slot 30 is sufficiently large to admit a head 32 formed at the end of the straight portion of the mandrel 7. This head 32 is separated from the main portion of the mandrel 7 by a square neck 33. When the piston 3 is retracted by movement to the right from the position of FIGURE 2, the two jaws 20 comprising the push surface 2 will contact the end of cylinder 1 and will thereby be rotated in the direction of arrows a and b to open the end of the piston 3 for insertion of the head 32 of the mandrel 7. The head 32 will be inserted into the piston 3 and inwardly of the surface 31 of the holding device 6 through utilization of the widened portion of the slot 30. This will place the head 32 of the mandrel in the full line position of FIGURE 3. The head 32 of the mandrel may now be dropped to its dotted line position of FIGURE 3 placing the square neck 33 within the narrow portion of the slot 30. It is rather obvious from FIGURE 2 that the mandrel will now be held against longitudinal movement outwardly of the holding device 6.

While I prefer the holding means just described, it is obvious that many other types of holding means may be utilized, the outstanding feature of the holding means being that they are within the hollow piston so that the push surface of the piston may itself fit on the mandrel and against the pipe sections.

I believe it will be rather clear now that when fluid is introduced at 10, the piston head 4 will be moved to the extreme right for opening the push surface portion of the piston 3 by movement of jaws 20, permitting the insertion and securing of a mandrel as just described. The mandrel will first, of course, have been loaded with a series of tubular pipe sections 12. When fluid is now introduced at 9, the piston head 4 will be moved to the left causing the hollow piston 3 and its push surface 2 to apply pressure to the end of the last of the pipe sections 12. All of the pipe sections will then be propelled over the mandrel 7 and bent within the furnace 13. Return of the piston 3 will now allow removal of the unloaded mandrel and the replacing thereof by a fully loaded mandrel for a second complete operation.

I now claim:

1. A pipe bending press comprising a hydraulic ram cylinder, a hollow piston slidably mounted in said cylinder, a push surface at the end of said piston having an opening for the insertion of one end of a pipe bending mandrel on which are mounted a series of pipe sections, and holding means within the hollow piston for holding the said one end of the mandrel against endwise movement out .of the hollow piston after said mandrel is inserted into the piston into engagement with said holding means.

2. In the combination of claim 1, the feature that the opening in the piston push surface permits the piston to move relatively to the mandrel for pushing a series of pipe sections fitted about said mandrel whereby to bend said pipe sections sequentially upon projection of said piston.

3. In the combination of claim 2, the feature that the opening in the piston push surface is of such size relatively to the mandrel that the piston and mandrel are held in guide relation to one another for the projection of said piston.

4. In the combination of claim 1, the feature that said holding means are mounted on a rod fixed to said ram cylinder and on which said piston slides.

5. In the combination of claim 1, the feature that said piston is fluid pressure projected in an outward push direction and in an inward retracting direction.

6. In the combination of claim 1, the feature that said holding means are in the form of a bayonet joint connection with said mandrel.

7. In the combination of claim 1, the feature that said push surface of said piston comprises parts movable relatively to said piston to expose its internal bore.

8. In the combination of claim 7, the feature that said parts are moved automatically when said piston is retracted to allow movement of said mandrel into said hollow piston and toward said holding means.

References Cited UNITED STATES PATENTS 1,095,265 5/1914 Brinkman 72--370 X 1,951,334 3/1934 Bohling. 1,962,510 6/1934 Kellogg. 2,234,863 3/ 1941 Heetkamp 72370 MILTON S. MEHR, Primary Examiner.

US. Cl. X.R. 

